1. Cut the ends off of the Brussels sprouts and remove any damaged leaves. Cut a small "x" into the bottom core of each sprout. 2. Boil the Brussels sprouts in salted boiling water just until tender. When they are done, remove them from the water and place in a bowl of ice water to chill them. When they are cold, remove from the water and cut each one in half through the core. Reserve. 3. Render bacon in a sauté pan until the bacon is well browned. Remove bacon. 4. Add onions to the sauté pan and cook until browned and tender. 5. Add Brussels sprouts and cook until they are hot. 6. Add cooked bacon, mustard, and maple. Cook until the maple reduces slightly and coats the Brussels sprouts. 7. Taste for seasoning and serve.